Motorcycle exhaust system

ABSTRACT

An exhaust system for an internal combustion engine having two banks of cylinders by which pulses of exhaust gas are alternately directed to a crossfire assembly. The crossfire assembly, which is located in the exhaust system, includes a gas accelerator chamber which divides each pulse of exhaust gas between two secondary exhaust outlets and causes a low pressure wave to occur in the exhaust system to enhance scavenging of a subsequent pulse of exhaust gas and thereby improve engine performance.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally exhaust systems. More particularly, theinvention relates to an exhaust system for a multi-cylinder internalcombustion engine.

2. Background

Motorcycles commonly employ exhaust systems to convey the exhaust gasfrom the engine's cylinder to the ambient environment. The journeybegins at the engine cylinder, which incorporates intake and exhaustports for ingress and egress to the cylinder. Fresh air mixed with fuelenters the engine cylinder through the intake port where it issubsequently compressed by a piston and ignited. A rapid expansion ofthe compressed fuel and air occurs, thereby forcefully moving the pistonin the opposite direction to the compression stroke. Once the expansionis complete, the exhaust port opens to allow the combustion by-productsor gas to exit the engine cylinder and enter an exhaust pipe. Theexhaust port may be a passageway into the engine cylinder that isuncovered by the retreating piston, as in a two-stroke design well knownin the art. In the case of a four-stroke design, a valve is utilized toopen or close the exhaust port. The exhaust gas expelled from the enginecylinder, after passing through the exhaust port, enters an exhaustpipe. The exhaust pipe is designed to direct the exhaust gas towards therear of the motorcycle and commonly utilizes bends and curves toaccomplish this goal.

In a single cylinder engine, the exhaust gas, after passing through theexhaust pipe, is typically fed into a muffler prior to its expulsioninto the atmosphere to dissipate unwanted noise originating in thecombustion process. The exhaust system may also include a catalyticconverter or other exhaust treatment device well known in the art. Themuffler design will significantly affect the audible noise level orsound of the engine. A manufacturer can attenuate or change the sound ofthe engine so as to not only meet governmental noise requirements butalso for the engine to exhibit a pleasing sound to the ear.

Depending on the design of the exhaust system, including the muffler andexhaust pipe, back pressure will be introduced, which impedes the freeflow of exhaust gases along the exhaust system's entire length. Forexample, in a four-stroke engine, the piston pushes the exhaust gasesout of the cylinder and into the exhaust system. If the back pressure inthe exhaust system is reduced, the piston requires less force to expelthe exhaust gases from the engine cylinder and thus increases theperformance and efficiency of the engine. The performance of an engineis measured by the engine's generation of, for example, horsepower andtorque over the entire rpm operating range. Generally, less backpressure will enhance the performance of the engine, or morespecifically the engine's production of horsepower and torque whileincreasing its efficiency or reducing the engine's fuel consumption.However, a significant reduction in back pressure, which may beaccomplished by, for example, using short exhaust pipes and no muffler,may have an adverse effect on engine noise and overall performance. Anexhaust system design that maximizes the horsepower of an engine willoften have a deleterious effect on the engine's torque production over aportion of the RPM range. If this drop in torque is located in themiddle of the RPM range, it may be noticeable as a momentary drop inacceleration to the rider or driver and be undesirable.

The overall length and shape of the exhaust system is an importantfactor in determining how the engine will operate and affect theperformance of the engine. For example, with a multi-cylinder engine itis commonly preferred to have individual exhaust systems for eachcylinder so as to prevent any flow turbulence caused by pulses ofexhaust gas from different cylinders combining before being expelled tothe atmosphere. However, individual exhaust systems may not be feasiblewhen the engine has more than two cylinders due to cost, size, weight,and packaging limitations. This concern is especially acute for amotorcycle since the exhaust system needs to fit close to the motorcycleframe so that the rider and passenger can straddle the motorcycle andnot be subjected to burns or the like caused by contact with the hotexhaust system. An automobile is less prone to the concern for unwantedcontact with the exhaust system as the car's floorpan is a barrierbetween the exhaust system and the occupants. A motorcycle, in a similarfashion, can incorporate bodywork to enclose the exhaust system tofurther protect the rider/passenger from the hot exhaust system. Thisbodywork may also act as a sound barrier to reduce the noise associatedwith the exhaust system. For an automobile, the length of the exhaustsystem may be increased to help dampen out the engine noise originatingin the combustion process, but this may not be well suited for amotorcycle due to a motorcycle's relatively short length as compared toan automobile.

The geometry or cross-sectional area of the exhaust system may also bevaried along its length to vary the engine's performance. Anever-increasing cross-sectional area in the exhaust system will decreasethe chance of causing a significant increase in back pressure. Aconstriction at any point in the exhaust system will have an impact onthe velocity of the pulses of exhaust gas throughout the entire exhaustsystem. But as with the length and shape of the exhaust system,continually increasing the cross-section in the exhaust system isdifficult to accomplish due to, for example, packaging and manufacturingconcerns. A compromise is to incorporate step increases in thecross-section of the exhaust system along its entire length. Forexample, a step increase in the exhaust system's inside diameter may beincorporated at each exhaust system flange connection from the exhaustpipe to the muffler.

Exhaust systems are commonly routed along the sides or below themotorcycle depending on such design factors as, for example, theorientation of the engine cylinders with respect to one another, theorientation of the engine in the motorcycle frame, the preferred ridingcharacteristics, the size of the motorcycle, and the location of themotorcycle's center of gravity. For example, a motorcycle with an engineinline with the frame can easily route its exhaust system along thesides of the motorcycle due to its narrow width. When the engine istransverse to the frame, there will be less available space to route theexhaust system along the sides of the frame due to the engine'sincreased width. In this case, the exhaust system may be routed belowthe engine and frame without increasing the overall width of themotorcycle. As a result of the many tradeoffs associated with the designof an exhaust system, a manufacturer will choose an exhaust system thatpresents a compromise between these characteristics for the consumer. Asdiscussed above, these characteristics may include, for example, cost,size, weight, engine noise, performance, and packaging limitations.

Customization of exhaust components by motorcycle riders, such asexhaust pipes and mufflers, is common in the aftermarket. Customizationallows the owner to re-optimize the characteristics of their vehicle soas to maximize their own satisfaction. A successful customization leadsto not only personal satisfaction of accomplishment, but also a feelingof attachment to the vehicle. Often, the replacement of a component madeby the original equipment manufacturer (OEM) with an aftermarket partdoes not live up to expectations and will not be easily reversible onceit is completed. This can lead to the owner incurring additional coststo reverse the modification. For example, the addition of a force airinduction system to an automobile often requires the cutting of a holein the hood over an engine. If the owner decided the additional noiseoutweighed the performance increase, the purchase of a new hood wouldhave to be absorbed to reverse the modification. In the case of exhaustsystems, incorporation of aftermarket components often requires cuttingand welding of the OEM exhaust system. Exhaust pipes or other parts ofthe exhaust system are often cut with subsequent welding being performedto incorporate the aftermarket component. Thus, the level of financialrisk being taken by the owner and difficulty in reversing themodification are increased.

In the case of the liquid-cooled, horizontally opposed six-cylinderHonda Gold Wing® engine, the design of the stock OEM exhaust manifoldaffects the motorcycle's performance by causing a perceptible drop intorque near the middle of the engine's RPM range at top-gear speeds ofbetween 50 and 75 mph. This drop in torque translates into less top-gearroll-on power which impacts the rider's ability to pass traffic athighway speeds with nothing more than the flick of the wrist. Except forthis perceptible drop in torque, the Gold Wing's® smoothness andexpansive torque make it one of the most rideable and satisfyingmachines on the market. Any potential aftermarket fix for thisperformance issue is further complicated by the Gold Wing's® OEM hiddenexhaust system which is enclosed by an OEM shroud, thus impeding anymodifications to the hidden exhaust system without permanent removal ofthe OEM shroud.

SUMMARY OF THE INVENTION

The preferred embodiment of the present invention is an exhaust systemfor a multi-cylinder motorcycle engine. The specific preferredembodiment described provides a substantial improvement to the wellknown Honda Gold Wing® engine. The aftermarket exhaust systemconstructed in recordance with the preferred embodiment of the inventioncomprises a plurality of primary exhaust pipes for dividing exhaustports of the multi-cylinder engine into first and second groups. Thefirst and second groups alternate in their discharge of a pulse ofexhaust gas from the engine and feed the pulse of exhaust gas into a gasaccelerator chamber which directs each alternating pulse of exhaust gasonto a flow splitter. The flow splitter, which is integral to the gasaccelerator chamber and located obliquely to the direction of exhaustgas flow, distributes each pulse of exhaust gas between a first exhaustoutlet and a second exhaust outlet forming a low-pressure zone in thewake of the pulse of exhaust gas. This low-pressure zone or wave travelsback up the primary exhaust pipes for a different group of exhaust portsto draw in or accelerate the subsequent pulse of exhaust gas out of thenext cylinder and down through the gas accelerator chamber. Thereby,scavenging of the pulse of exhaust gas from the engine cylinder isincreased.

One significant feature of the preferred embodiment of this invention isthat it provides the benefits of using a collector in an exhaust system,such as minimizing cost, weight and packaging while avoiding thepossible interference between pulses of exhaust gases combining in thecollector. Combining of the exhaust pipes can lead to an increase inback pressure and the corresponding drop in engine performance. However,in the present invention, the combination of pulses of exhaust gasincreases the performance of the engine by enhancing scavenging. As aresult, exhaust systems constructed in accordance with the preferredembodiment of this invention actually increase the exit velocity of theexhaust gas from the engine cylinder.

Another feature of the preferred embodiment of this invention is thateach cylinder has substantially its own equal length exhaust pipe. Thismeans each exhaust pipe is routed between the exhaust port and thecollector such that all of the exhaust pipes have the same overalllength. The exhaust pipes feed into a single collector. The benefit tousing equal length exhaust pipes is that the pulses of exhaust gas willnot arrive at the same time at the collector, which minimizes anyinterference between the pulses.

Still another feature of the preferred embodiment of the invention isthat it emits a strong, throaty rumble typically preferred by rider oftouring bikes typically prefer an exhaust system designed to emit, yetnot so loud as to cause undue rider fatigue on a long road trip. Incontrast, the OEM exhaust system for the Honda Gold Wing® was designedto minimize the exhaust sound of the motorcycle and presents asignificant compromise to the owner of this powerful six-cylindermotorcycle sin an almost whisper quite engine does not audibly projectthe high level of performance associated with a powerful six-cylinderengine.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objectives, and advantages of the preferred embodiment ofthe invention will become more apparent from the detailed descriptionset forth below when taken in conjunction with the drawings wherein likeparts are identified with like reference numerals throughout, andwherein:

FIG. 1 is a top plan view showing an exhaust system according to apreferred embodiment of the invention.

FIG. 2 is a perspective view of the crossfire assembly in accordancewith the preferred embodiment of the invention.

FIG. 3A is a top perspective view of the gas accelerator chamber that isa component of the crossfire assembly shown in FIG. 2.

FIG. 3B is a bottom perspective view of the gas accelerator chamber thatis a component of the crossfire assembly shown in FIG. 2.

FIG. 4 is a side elevational view of one embodiment of the crossfireassembly incorporated into a motorcycle in accordance with the preferredembodiment of the invention.

FIG. 5 is a side perspective view of a portion of the motorcycle exhaustsystem encompassed within line 5 of FIG. 4 and shows the crossfireassembly of the preferred embodiment of the present invention.

FIG. 6A is graphical view showing the torque curves of the Honda GoldWing® engine with its OEM factory exhaust system (shown by the brokencurve line labeled “stock”) and the same engine with an aftermarketexhaust system constructed in accordance with the preferred embodimentof the invention (shown by the solid curve line labeled “Bassani”).

FIG. 6B is a graphical view showing the horsepower curves of the HondaGold Wing® engine with its OEM factory exhaust system (shown by thebroken curve line labeled “stock”) and the same engine with anaftermarket exhaust system constructed in accordance with the preferredembodiment of the invention (shown by the solid curve line labeled“Bassani”).

FIG. 7 is a top perspective view of the crossfire assembly shown in FIG.2.

FIG. 8 is a bottom perspective view of the crossfire assembly shown inFIG. 2.

FIG. 9 is a side perspective view of the crossfire assembly of FIG. 2,taken on the opposite side of the motorcycle to that of FIG. 5.

FIG. 10 is a front perspective view of the crossfire assembly shown inFIG. 2.

FIG. 11 is a rear perspective view of the crossfire assembly shown inFIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a top plan view showing an exhaust system according to thepreferred embodiment of the invention. An internal combustion engine 20has two cylinder banks 22, 24 in an opposed arrangement. The twocylinder banks 22, 24 consist of a plurality of cylinders 26, 28,respectively. In the embodiment of the invention shown in FIG. 1, thetwo cylinder banks 22, 24 comprise three left and three right cylindersfrom the plurality of cylinders 26, 28. Each of the two cylinder banks22, 24 have fixedly attached a cylinder head 30, 32 which forms aplurality of combustion chambers (not shown) within each plurality ofcylinders 26, 28. Each cylinder head 30, 32 incorporates at least one ofa plurality of intake ports (not shown) and at least one of a pluralityof exhaust ports 34 for ingress and egress to the plurality of cylinders26, 28. The intake ports are connected to an intake system (not shown)where fresh air mixed with fuel enters the plurality of engine cylinders26, 28 where it is subsequently compressed by a plurality of pistons(not shown) into the plurality of combustion chambers (not shown) andignited. A rapid expansion of the compressed fuel and air occurs,thereby forcefully moving the plurality of pistons in the oppositedirection to the compression stroke.

The ignition of the compressed fuel and air occurs in an alternatingsequence whereby one of the plurality of cylinders 26 transmits a pulseof exhaust gas followed by the transmission of another pulse of exhaustgas from one of the plurality of cylinders 28. In the embodiment shownin FIG. 1, this sequence is in the order of A-B-C-D-E-F and continuallyrepeats during the operation of the internal combustion engine 20. Oncethe rapid expansion of the compressed fuel and air is complete, one ofthe plurality of exhaust ports 34, which is in flow communication withthe ignited engine cylinder 26, 28, opens to allow the combustionby-products or pulse of gas to exit through the cylinder head 30, 32 andinto a plurality of primary exhaust pipes 36, 38.

The plurality of primary exhaust pipes 36, 38 have a plurality of inletends (not shown) which are connected to the plurality of exhaust ports34 to scavenge each pulse of exhaust gas from the plurality of enginecylinders 26, 28. Each of the primary exhaust pipes 36, 38 areconfigured to be in flow communication with each of the cylinders 26, 28and are brought together into one of two collector chambers 40, 42 foreach of the two cylinder heads 30, 32. Each of the two collectorchambers 40, 42 is connected to and in flow communication with at leastone outlet end (not shown) of each plurality of primary exhaust pipes36, 38, wherein the two collector chambers 40, 42 alternate in theircollection of subsequent discharges of the pulse of exhaust gas from theinternal combustion engine 20. The two collector chambers 40, 42 arefurther connected to a crossfire assembly 44.

The use of the collector chambers 40, 42 has the benefits of, forexample, minimizing cost, weight and packaging, but may be outweighed bythe possible interference between pulses of exhaust gas combining in thecollector chambers 40, 42. This combining of each plurality of primaryexhaust pipes 36, 38 may lead to an increase in back pressure and thecorresponding drop in engine performance. However, the combination ofpulses of exhaust gas in the preferred embodiment of the presentinvention increases the performance of the internal combustion engine 20by enhancing scavenging. Scavenging is the process of removing theexhaust gases from the cylinders. Scavenging may be enhanced or reducedby the collector chambers 40, 42 of the pulses of exhaust gas dependingon the design of the exhaust system coupled with the design of theinternal combustion engine 20. A properly scavenged engine will actuallyincrease the exit velocity of the pulse of exhaust gas from theplurality of cylinders 26, 28. In a four-stroke engine, this reduces theforce required by the piston to expel the pulse of exhaust gas from theplurality of cylinders 26, 28.

In another embodiment of the invention, the collector chambers 40, 42may take the form of a series of Y connections (not shown) in an exhaustsystem. For example, in a four-cylinder engine four primary exhaustpipes (not shown) may be combined in pairs using two Y-collectors (notshown) and further combined with an additional Y-collector into a singleexhaust pipe (not shown). For an eight-cylinder engine, this processwould be mirrored for the opposite bank of four cylinders such that eachbank would be combined using three Y-collectors into two exhaust pipes(not shown). The collector (not shown) may be placed anywhere in theexhaust system or incorporated in an exhaust system component which iswell known in the art. For example, the collector could be locatedadjacent to where the gas leaves the exhaust ports of the cylinder orincorporated into the muffler (not shown).

In still another embodiment of the invention, the plurality of cylinders26, 28 each have their own equal length primary exhaust pipe (notshown). This means each primary exhaust pipe 36, 38 is routed betweenthe plurality of exhaust ports 34 and the collector chambers 40, 42 suchthat all of the plurality of primary exhaust pipes have the same overalllength. Each plurality of primary exhaust pipes feeds into one of thetwo collector chambers 40, 42 as opposed to multiple Y-collectors asdiscussed above. The benefit to using equal length primary exhaust pipesis that the pulses of exhaust gas will not arrive at the same time ateach of the collector chambers 40, 42, which minimizes any interferencebetween the pulses.

The operation of the crossfire assembly 44 may be understood uponreference to FIG. 2, which is a perspective view of the crossfireassembly 44 in accordance with the invention. The crossfire assembly 44receives the pulse of exhaust gas by way of two s-tube pipes 46, 48 eachconnected to and in flow communication with one of the two collectorchambers 40, 42. The two s-tube pipes 46, 48 are each formed from a pairof approximately 180-degree elbow pipes (not shown) attached end to endin the shape of a non-coplanar “S” to form flow conduits between the twocollector chambers 40, 42 and a gas accelerator chamber 50.

Referring to FIGS. 3A-3B, which are top and bottom perspective views ofthe gas accelerator chamber 50, respectively, that is a component of thecrossfire assembly 44 shown in FIG. 2. Flow into and out of the gasaccelerator chamber 50 is achieved by way of two exhaust inlets 52, 54and two exhaust outlets 56, 58. The two exhaust inlets 52, 54 are formedby two overlapping circular shapes whereby their intersection forms twogrooved surface depressions 60 which meld smoothly into the surface ofthe gas accelerator chamber 50. Exhaust inlet 52 is in flowcommunication with s-tube pipe 46; and exhaust inlet 54 is in flowcommunication with s-tube pipe 48. Crossing the two s-tube pipes 46, 48(FIG. 2) increases the overall length of the flow path by an amountsufficient for the pulse of exhaust gas to dampen exhaust noise andfurther aligns the pulse of exhaust gas for its entrance into the gasaccelerator chamber 50.

The exhaust inlets 52, 54 are aligned to direct the pulse of exhaust gastravelling from the two s-tube pipes 46, 48 onto a flow splitter 62which may be integral to the gas accelerator chamber 50. The outersurface of the flow splitter 62 is primarily concave with the innersurface being primarily convex. The flow splitter 62 is locatedobliquely to the flow direction of the pulse of exhaust gas to divideeach pulse of exhaust gas between the two exhaust outlets 56, 58. Thetwo exhaust outlets 56, 58 direct each distributed pulse of exhaust gasaway from the flow splitter 62 forming a low-pressure zone (not shown)in the wake of the pulse of exhaust gas. The low-pressure zonepreferentially travels back up the exhaust system towards the pluralityof exhaust ports 34 to scavenge the subsequent pulse of exhaust gas.

In one embodiment of the invention, the gas accelerator chamber 50 isfabricated by welding two similar upper and lower halves 64 together. Instill another embodiment, the two exhaust inlets 52, 54 are formed bynon-overlapping circular shapes designed to accept the two s-tube pipes46, 48.

Each of the two exhaust outlets 56, 58 are in flow communication with amuffler 66 (FIG. 1) by way of two secondary exhaust pipes 68 (FIG.3A-3B) so that the pulse of exhaust is expelled through both mufflers 66(FIG. 1) to the atmosphere. In one preferred embodiment, the insidediameter of the two s-tube pipes 46, 48 (FIG. 2) is equal to or greaterthan the inside diameter of each of the primary exhaust pipes 36, 38(FIG. 1) but less than or equal to the inside diameter of the twosecondary exhaust pipes 68 (FIG. 1).

In one preferred embodiment of the invention, as illustrated in FIG. 4,the Honda Gold Wing® motorcycle 70 is shown with the crossfire assembly44 incorporated into Honda Gold Wing® OEM exhaust system. A feature ofthis preferred embodiment is that the OEM exhaust shroud (not shown) isretained so as to maintain the integrity of the OEM hidden exhaustsystem. The installation of the crossfire assembly 44 merely requiresthe translation of both OEM exhaust mufflers 72 approximately 1.5 inchestowards the rear of the motorcycle. Such translation does not requireany permanent modification to the Honda Gold Wing® 70.

FIG. 5 is a side perspective view of a portion of the motorcycle exhaustsystem encompassed within line 5 of FIG. 4 and shows the crossfireassembly 44 of the present invention connected to one of the OEM exhaustmufflers 72 and one of two OEM collector chambers 74.

FIG. 6A is a graphical view showing two torque curves of the Honda GoldWing® 70 of FIG. 4 and FIG. 6B is a graphical view showing twohorsepower curves for the same engine. The solid lines 76, 78,respectively, show the torque and horsepower curves for the Honda GoldWing® 70 using the motorcycle exhaust system constructed in accordancewith the preferred embodiment of this invention. The improvement in thehorsepower and torque values across the RPM range are readily apparentfrom these graphs when compared to the torque and horsepower curvesusing the stock OEM exhaust system of the Honda Gold Wing® 70 (shownrespectively by dashed lines 80, 82). The increase in performance causedby the crossfire assembly 44 is even more pronounced around 3,100 RPM.As shown, around this RPM the stock OEM exhaust manifold causes aperceptible drop in torque at top-gear speeds of between 50 and 75 mph.This drop in torque translates into less top-gear roll-on power whichimpacts the rider's ability to pass traffic at highway speeds withnothing more than the flick of the wrist. In addition, incorporation ofthe crossfire assembly 44 overcomes the Honda Gold Wing® engine's lackof a strong, throaty rumble being emitted from its stock exhaust system.

Referring now to FIG. 7, the crossfire assembly 44, of FIG. 2, is shownin a top perspective view with the two s-tube pipes 46, 48 forming anacute angle so that each of the two s-tube pipes 46, 48 are in line withthe flow splitter 62. Thus causing an equal distribution of the pulse ofexhaust gas between the two exhaust outlets 56, 58.

FIG. 8 is a bottom perspective view of the crossfire assembly 44, ofFIG. 2, showing a bracket 84 fixedly attached to one of the twosecondary exhaust pipes 68. The bracket is configured to allow the useof a stock attachment point for the installation of the crossfireassembly 44 on the Honda Gold Wing® 70.

FIG. 9 is a side perspective view of the crossfire assembly 44, of FIG.2, taken on the opposite side of the motorcycle to that of FIG. 5showing a bracket 86 fixedly attached to the s-tube pipe 46. The bracketis configured to allow the use of a stock attachment point for theinstallation of the crossfire assembly 44 on the Honda Gold Wing® 70.

FIG. 10 is a front perspective view of the crossfire assembly 44 shownin FIG. 2. A bracket 88 is shown fixedly attached to the s-tube pipe 48of the crossfire assembly 44 in FIG. 2. A triangle shaped piece 90 isshown attached at the intersection of the two s-tubes 46, 48 to seal thegas accelerator chamber 50 (not shown).

FIG. 11 is a rear perspective view of the crossfire assembly 44, of FIG.2, showing the flow splitter 62 of the gas accelerator chamber 50 (notshown).

The invention may be embodied in other specific forms without departingfrom its spirit or essential characteristics. The described embodimentis to be considered in all respects only as illustrative and notrestrictive and the scope of the invention is, therefore, indicated bythe appended claims rather than the foregoing description. All changeswhich come within the meaning and range of equivalency of the claims areto be embraced within their scope.

What is claimed is:
 1. An exhaust system for a Honda Gold Wing®motorcycle with a horizontally opposed six-cylinder engine with adisplacement of 1520 cc, wherein the exhaust system increases theengine's performance and incorporates the OEM shroud covering the OEMexhaust manifold, said system comprising: a plurality of exhaust ports,each in communication with a cylinder of the engine to discharge a pulseof exhaust gas; a plurality of primary exhaust pipes, each having aninlet end and an outlet end, wherein the inlet end is connected to oneof the exhaust ports to scavenge the pulse of exhaust gas; two collectorchambers, each connected to and in flow communication with at least oneoutlet end of the plurality of primary exhaust pipes, wherein the twocollector chambers alternate in their collection of subsequentdischarges of the pulse of exhaust gas from the engine; two s-tubepipes, each connected to and in flow communication with one of thecollector chambers and formed from a pair of approximately 180 degreeelbow pipes attached at one of their ends in the shape of a non-coplanars-tube, and wherein the two s-tube pipes cross each other; a gasaccelerator chamber connected to and in flow communication with both ofthe s-tube pipes, wherein the gas accelerator chamber has two exhaustinlets and two exhaust outlets, wherein each exhaust inlet is aligned todirect the pulse of exhaust gas onto a flow splitter which is in the gasaccelerator chamber, wherein the flow splitter is located obliquely tothe flow direction of the pulse of exhaust gas to divide the pulse ofexhaust gas between the two exhaust outlets, wherein the two exhaustoutlets direct the distributed pulse of exhaust gas away from the flowsplitter forming a low-pressure zone in the wake of the pulse of exhaustgas, and wherein the low-pressure zone preferentially travels back upthe exhaust system to scavenge the subsequent pulse of exhaust gas; twosecondary exhaust pipes, each having an upstream end and a downstreamend, wherein each upstream end is connected to and in flow communicationwith one of the two exhaust outlets; two exhaust mufflers, eachconnected to and in flow communication with one of the downstream endsof the two secondary exhaust pipes, wherein the pulse of exhaust gas isexpelled through both mufflers to the atmosphere; and wherein the insidediameter of the s-tube pipes is equal to or greater than the insidediameter of the plurality of primary exhaust pipes but less than orequal to the inside diameter of the two secondary exhaust pipes.
 2. Anexhaust system according to claim 1, wherein the flow splitter has aconvex shape and is integral with a surface of the gas acceleratorchamber.
 3. An exhaust system of a multi-cylinder engine, said systemcomprising: a plurality of exhaust ports of the multi-cylinder enginewhich are equally split between a first group and a second group,wherein the first group and the second group alternate in the dischargeof a pulse of exhaust gas from the engine; and a gas accelerator chamberhaving a first exhaust inlet and a second exhaust inlet aligned todirect the pulse of exhaust gas from the first group and the secondgroup onto a flow splitter, wherein the flow splitter is in the gasaccelerator chamber and located obliquely to the direction of exhaustgas flow to distribute the pulse of exhaust gas between a first exhaustoutlet and a second exhaust outlet, and wherein the first and secondexhaust outlets direct the distributed pulse of exhaust gas away fromthe flow splitter.
 4. An exhaust system according to claim 3, furthercomprising: a first downstream pipe with a first entrance end and afirst exit end, wherein the first entrance end is connected to the firstexhaust outlet and the first exit end is connected to a first muffler;and a second downstream pipe with a second entrance end and a secondexit end, wherein the second entrance end is connected to the secondexhaust outlet and the second exit end is connected to a second muffler.5. An exhaust system according to claim 4, further comprising: a firsts-tube pipe with a first inlet end and a first outlet end, wherein thefirst inlet end is connected to a first exhaust pipe from the firstgroup of exhaust outlets and the first outlet end is connected to thefirst exhaust inlet; a second s-tube pipe with a second inlet end and asecond outlet end, wherein the second inlet end is connected to a secondexhaust pipe from the second group of exhaust outlets and the secondoutlet end is connected to the second exhaust inlet; wherein the firsts-tube pipe and the second s-tube pipe cross each other; and wherein thefirst and second s-tube pipes and the first downstream pipe are fixedlyattached to external brackets for attachment to an adjacent structure ofa motorcycle.
 6. An exhaust system according to claim 4, furthercomprising: a first s-tube pipe with a first inlet end and a firstoutlet end, wherein the first inlet end is connected to a first exhaustpipe from the first group of exhaust outlets and the first outlet end isconnected to the first exhaust inlet; a second s-tube pipe with a secondinlet end and a second outlet end, wherein the second inlet end isconnected to a second exhaust pipe from the second group of exhaustoutlets and the second outlet end is connected to the second exhaustinlet; wherein the first s-tube pipe and the second s-tube pipe crosseach other; and wherein the s-tube pipes, the gas accelerator chamber,and the downstream pipes are configured to replace an original equipmentmanufacture (OEM) exhaust manifold of a Honda Gold Wing® motorcycle witha horizontally opposed six-cylinder engine with a displacement of 1520cc.
 7. An exhaust system according to claim 6, wherein the s-tube pipes,the gas accelerator chamber, and the downstream pipes fit within theexisting shroud that contains the OEM exhaust manifold.
 8. An exhaustsystem according to claim 7, wherein the replacement of the OEM exhaustmanifold is configured to not require any permanent modification of theremaining OEM exhaust system of the Honda Gold Wing® motorcycle.
 9. Anexhaust system according to claim 8, wherein an OEM muffler is shiftedto the rear less than 2 inches with respect to the motorcycle toaccommodate the replacement of the OEM exhaust manifold.
 10. An exhaustsystem according to claim 3, further comprising: a first s-tube pipewith a first inlet end and a first outlet end, wherein the first inletend is connected to a first exhaust pipe from the first group of exhaustoutlets and the first outlet end is connected to the first exhaustinlet; a second s-tube pipe with a second inlet end and a second outletend, wherein the second inlet end is connected to a second exhaust pipefrom the second group of exhaust outlets and the second outlet end isconnected to the second exhaust inlet; and wherein the first s-tube pipeand the second s-tube pipe cross each other.
 11. An exhaust systemaccording to claim 10, wherein the gas accelerator chamber is fabricatedby welding an upper half and a lower half together, wherein the upperand lower halves are identical.
 12. An exhaust system according to claim11, wherein the upper half and the lower half each have a groovedsurface depression creating a cleavage between the first exhaust inletand second exhaust inlet; and wherein the combination of the cleavage,the first and second exhaust inlets form two partial circles to improvethe fit of the first and second exhaust inlets with the first and secondoutlet ends.
 13. An exhaust system of a multi-cylinder engine, saidsystem comprising: a plurality of exhaust ports of the multi-cylinderengine which are equally split between a first group and a second group,wherein the first group and the second group alternate in the dischargeof a pulse of exhaust gas from the engine; a gas accelerator chamberhaving a first exhaust inlet and a second exhaust inlet aligned todirect the pulse of exhaust gas from the first group and the secondgroup onto a flow splitter, wherein the flow splitter is in the gasaccelerator chamber and located obliquely to the direction of exhaustgas flow to distribute the pulse of exhaust gas between a first exhaustoutlet and a second exhaust outlet, and wherein the first and secondexhaust outlets direct the distributed pulse of exhaust gas away fromthe flow splitter; a first s-tube pipe with a first inlet end and afirst outlet end, wherein the first inlet end is connected to a firstexhaust pipe from the first group of exhaust outlets and the firstoutlet end is connected to the first exhaust inlet: a second s-tube pipewith a second inlet end and a second outlet end, wherein the secondinlet end is connected to a second exhaust pipe from the second group ofexhaust outlets and the second outlet end is connected to the secondexhaust inlet; wherein the first s-tube pipe and the second s-tube pipecross each other; and wherein the first and second s-tube pipes are eachmade from a pair of approximately 180 degree elbow pipes attached at oneof their ends to form the shape of a non-coplanar s-tube.
 14. An exhaustsystem of a multi-cylinder engine, said system comprising: a pluralityof exhaust ports of the multi-cylinder engine which are equally splitbetween a first group and a second group, wherein the first group andthe second group alternate in the discharge of a pulse of exhaust gasfrom the engine; a gas accelerator chamber having a first exhaust inletand a second exhaust inlet aligned to direct the pulse of exhaust gasfrom the first group and the second group onto a flow splitter, whereinthe flow splitter is in the gas accelerator chamber and locatedobliquely to the direction of exhaust gas flow to distribute the pulseof exhaust gas between a first exhaust outlet and a second exhaustoutlet, and wherein the first and second exhaust outlets direct thedistributed pulse of exhaust gas away from the flow splitter; a firsts-tube pipe with a first inlet end and a first outlet end, wherein thefirst inlet end is connected to a first exhaust pipe from the firstgroup of exhaust outlets and the first outlet end is connected to thefirst exhaust inlet; a second s-tube pipe with a second inlet end and asecond outlet end, wherein the second inlet end is connected to a secondexhaust pipe from the second group of exhaust outlets and the secondoutlet end is connected to the second exhaust inlet; wherein the firsts-tube pipe and the second s-tube pipe cross each other; wherein thefirst and second s-tube pipes are each made from a pair of approximately180 degree elbow pipes attached at one of their ends to form the shapeof a non-coplanar s-tube; wherein the inside diameter of the firsts-tube pipe is equal to or greater than the inside diameter of the firstexhaust pipe but less than or equal to the inside diameter of the firstdownstream pipe; and wherein the inside diameter of the second s-tubepipe is equal to or greater than the inside diameter of the secondexhaust pipe but less than or equal to the inside diameter of the seconddownstream pipe.
 15. A method of processing exhaust gases from amulti-cylinder engine, wherein a pulse of exhaust gas is produced in acylinder of the multi-cylinder engine, said method comprising the stepsof: routing the pulse of exhaust gas in a flow path from the cylinder toone of a two collector chambers, wherein the two collector chambersalternate in their collection of subsequent discharges of the pulse ofexhaust gas; aligning the flow path of the pulse of exhaust gas with aflow splitter located in a gas accelerator chamber, wherein the gasaccelerator chamber is in flow communication with both collectorchambers; dividing the pulse of exhaust gas into a two substantiallyequal portions of exhaust gas by way of contact with the flow splitter;and expelling both substantially equal portions of exhaust gas from thegas accelerator chamber via a two exhaust outlets in the gas acceleratorchamber and into the atmosphere.
 16. An apparatus for processing exhaustgases from a multi-cylinder engine, wherein a pulse of exhaust gas isproduced in a cylinder of the multi-cylinder engine, said apparatuscomprising: means for routing the pulse of exhaust gas in a flow pathfrom the cylinder to one of a two collector chambers, wherein the twocollector chambers alternate in their collection of subsequentdischarges of the pulse of exhaust gas; means for aligning the flow pathof the pulse of exhaust gas with a flow splitter located in a gasaccelerator chamber, wherein the gas accelerator chamber is in flowcommunication with both collector chambers; means for dividing the pulseof exhaust gas into a two substantially equal portions of exhaust gas byway of contact with the flow splitter; and means for expelling bothsubstantially equal portions of exhaust gas from the gas acceleratorchamber via a two exhaust outlets in the gas accelerator chamber andinto the atmosphere.
 17. A motorcycle comprising: a frame; amulti-cylinder engine attached to the frame and having two cylinderheads, each containing at least one cylinder; and a gas acceleratorchamber in flow communication with the two cylinder heads, wherein thegas accelerator chamber has a first exhaust inlet and a second exhaustinlet aligned to direct a pulse of exhaust gas from the cylinder headsonto a flow splitter, wherein the flow splitter is in the gasaccelerator chamber and located obliquely to the direction of exhaustgas flow to distribute the pulse of exhaust gas between a first exhaustoutlet and a second exhaust outlet, and wherein the first and secondexhaust outlets direct the distributed pulse of exhaust gas away fromthe flow splitter.